As is known, the increasing use of portable apparatuses—such as laptops, PDAs (Personal Data Assistants), digital audio players, cellphones, digital camcorders, and the like—or electronic apparatuses in general (personal computers, consoles for videogames and associated peripherals, etc.) has led to an increasing need to simplify use thereof, in particular as regards the user interface. In this connection, the possibility of activating given functions or programs of these apparatuses by a simple user control action directly involving the electronic apparatus has been considered of particular interest (for example, a displacement or an inclination of the apparatus, or a force or pressure exerted on the same apparatus).
For this purpose, in some electronic apparatuses, sensor devices have been introduced for detection of control actions imparted by the user (for example, inertial sensors, such as accelerometers or gyroscopes). In particular, the use of MEMS (micro-electromechanical systems) sensors, made with semiconductor technologies, has proven advantageous given their small dimensions and consequent small area occupation. A microprocessor circuit, supervising the general operation of the electronic apparatus, is able to determine user control actions and to activate corresponding functions or programs within the apparatus, via monitoring of the detection signals generated by the sensor devices.
Moreover, the use of detection signals coming from sensor devices on board the electronic apparatuses has been proposed for recognition, via suitable processing operations, of particular apparatus conditions, such as for example, a condition of free fall, or of reactivation from stand-by (wake-up function).
Solutions of this sort, although having the potential advantage of simplifying the interface and improving the general functionality of electronic apparatuses, have the problem of burdening the apparatus microprocessor circuit with continuous monitoring of the detection signals from the sensor devices, and processing of the same signals for recognition of the control actions exerted by the user or of the aforesaid conditions (more in general, of “events” associated to the electronic apparatuses). There follows a general degradation of the performance of the electronic apparatus, and/or a poor promptness thereof in recognizing the aforesaid events.
In order to overcome this problem, the integration within the sensor devices of event-recognition related functions has recently been proposed. In particular, a dedicated integrated circuit has been associated to a detection structure of these devices, the circuit being designed to carry out simple processing operations based on the signals generated by the detection structure for recognition of given events (for example, free-fall or wake-up events). Upon recognition of an event, the integrated circuit generates an interrupt signal for the microprocessor circuit of the electronic apparatus that incorporates the sensor device so that it can promptly activate appropriate actions associated to the detected event, this without using internal resources for event recognition.
However, also due to the small amount of resources and the small area available for integration within the sensor devices, the aforesaid integrated circuits are not currently able to carry out complex processing operations on the detection signals, necessary for example, for recognition of particular (e.g., multiple) events, so that the computational burden for the microprocessor circuits on board the portable apparatuses in given applications remains high.